SFB 668


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12.7.2011, 17:00
Jungiusstr. 11, Hörsaal AP

SFB 668 - Kolloquium

Prof. Dr. Frithjof Nolting (Uni Basel / PSI):

A close look at magnetic multilayers and nanomagnets with X-ray microscopy

Exploring the world of reduced dimensions in solid state physics is a challenging and rewarding research area. A powerful tool to investigate the magnetic properties of nanoscale systems is X-ray photoemission electron microscopy (XPEEM) employing X-ray magnetic linear dichroism (XMLD) and X-ray magnetic circular dichroism (XMCD) [1]. Using recent results I will explain the technique and its possibilities. One example is the study of magnetic multilayers where we search for ways to control the magnetization of a medium by means other than magnetic fields. Recently, it has been demonstrated that laser-excitation of a bulk antiferromagnet may result in subpicosecond modification of magnetic anisotropy followed by 90-degree reorientation of antiferromagnetic spins within few picosecond. Here we present experimental results on the laser control of spins in ferromagnet-antiferromagnet heterostructure Co/SmFeO3. Another example is the study of the magnetic properties and scaling laws of nanoparticles. Using PEEM, we discovered a size-dependent transition from a single domain state to a non-collinear spin structure in isotropic nanoparticles with sizes ranging from 25 down to 5 nm [2]. Further examples will be about patterned magnetic nanostructures [3] and how the magnetization of ferromagnetic systems can be manipulated by ultrashort laser pulses. [1] F. Nolting, A. Scholl, J. Stöhr, J.W. Seo, J. Fompeyrine, H. Siegwart, J.-P. Locquet, S. Anders, J. Lüning, E.E. Fullerton, M.F. Toney, M.R. Scheinfein, and H.A. Padmore, Nature 405, 767 (2000). [2] Fraile Rodríguez, A. Kleibert, J. Bansmann, A. Voitkans, L. J. Heyderman, and F. Nolting, Phys. Rev. Lett. 104, 127201 (2010). [3] E. Mengotti, L. J. Heyderman, A. Fraile Rodríguez, F. Nolting, R.V. Hügli, and H. B. Braun, Nature Physics Nature Physics 7, 68 (2011).

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